HTML/CSS/Text Attributes/datetime
"datetime" sets the date and time when the text in a "del" or "ins" element was deleted
<HTML>
<BODY>
<del datetime="2006-04-15T18:50:30Z">deleted</del>
</BODY>
</HTML>
<HTML>
<BODY>
<del datetime="2006-04-15T18:50:30Z">deleted</del>
</BODY>
</HTML>